LOS ANGELES, March 6, 2004 — The Mars rovers moved toward new rocks to drill on Saturday, a day after the Spirit rover found geological evidence that the dusty Red Planet had a wet past.

The Opportunity rover prepared for another drilling job as Spirit — positioned halfway around the planet — rolled slowly toward the rim of a crater called “Bonneville.”

The six-wheeled Spirit moved 94 feet (28 meters) northeast toward the crater after snapping the final photographs that scientists will use to assemble a full-circle, full-color panorama of the region dubbed “Middle Ground.”

Meanwhile, Opportunity used its tool-laden robotic arm to inspect a rock called “Wave Ripple” and took 50 microscopic images. It then drove to a new target at the south end of the outcropping that it has been examining for weeks. Its wheels slipped in the soil and it had to move along a slight slope, but the job was accomplished.

Opportunity planned to use its rock abrasion tool to grind away on a feature called “Flat Rock” over the weekend.

NASA’s $820 million rover mission was designed to seek geological clues on whether ancient Mars had enough water to have supported life, and both rovers have now found evidence of past water activity on the planet.

NASA announced Friday that the Spirit rover’s instruments found signs that water may have altered a volcanic rock in a region called Gusev Crater. The crater is halfway around the planet from where Opportunity earlier uncovered evidence that its landing site was once drenched.

The amount of water suggested by the data is far less than what Opportunity found at its site.

An earlier version of this report misstated the cost of the Mars missions.